There are very few things that education researchers say they know with absolute certainty, but virtually nobody disputes that socioeconomic status, cultural identity and the educational level of parents — especially mothers — are linked to the stubborn achievement gap between students of different races and ethnicities.

Children from poor families do worse than kids from middle-class and wealthy families; children do better if their mother has a college degree; and, overall, children of all ethnicities and races do better in schools with less than 25 percent of the student population coming from low-income families.

The issue of how much out-of-school influences affect how well a child does in school has become controversial in today’s education debate, with many reformers insisting that a great teacher can overcome much, if not all, of the outside factors.

Critics of this thinking say that research has shown that outside factors are generally more powerful than any teacher and that it is the exception rather than the rule that students facing myriad social issues can do well at school without any attention being given to remediate those problems.

Where is the gap the worst?

According to2011 national testing data , the gap between white and black students is wider in D.C. public schools than in any other urban district — despite efforts by former chancellor Michelle A. Rhee and current schools chief Kaya Henderson to close it. The same holds true for the gap between white and Hispanic students.

The persistent gap in the District reflects on the questionable nature of some of the reforms that have been implemented in the city and elsewhere around the country — which too often ignore the outside-of-school influences that affect how well a student does in class.

By the numbers

Here are some new statistics from a study of gaps in educational access and persistence just released by the U.S. Education Department’s National Center for Education Statistics.

The statistics tell the story. The following refer to the 2010-11 school year, the latest year for which statistics are available:

●About 21 percent of children younger than 18 were living in poverty. (In 2011, the Census Bureau released new figures that showed that 22 percent of American children were living in poverty.)

●The percentage of students in low- and high-poverty public elementary and secondary schools by race/ethnicity and sex tells a big part of the story. In the 2010-11 school year, for example, 6 percent of whites were in high-poverty schools, where more than 75 percent of students are eligible for free or reduced-price lunch, a measure the federal government uses to determine poverty.

Fifteen percent of Asian students were, too. But 42 percent of black students were in these schools, 38 percent of Hispanics, 31 percent of American Indian/Native Alaskans and 19 percent of Pacific Islanders.

●About 11 percent of children between 6 and 18 lived in a household where neither parent had earned at least a high school credential (either a diploma or an equivalency credential such as a GED certificate).

●The poverty rate for children living with a female parent with no spouse present was 44 percent. Broken down, the numbers were 52.8 percent for American Indians; 51.3 percent for blacks; 49.6 percent for Hispanics; 35.1 percent for whites; 33.2 percent for Native Hawaiian/Pacific Islanders; and 29.3 percent for Asians.

●The percentage of children ages 6 to 18 whose parents’ highest level of educational attainment was less than high school completion helps tell the achievement gap story. The average percentage was 11 percent for males and females, but 31 percent of Hispanic children had parents who had not completed high school, 11 percent of black kids, 10 percent of Asian males and 9 percent of Asian females.

●Twenty-two percent of the school-age population, or 11.8 million children 5 to 17, spoke a language other than English at home; 2.7 million spoke English with difficulty. The breakdown: 16 percent for Hispanics, 16 percent for Asians, 7 percent for Native Alaskans, 5 percent for Native Hawaiians/Pacific Islanders; 2 percent for American Indians, and 1 percent for black students and 1 percent for white pupils.

●In 2009, the latest year for which statistics were available for this item, 13 percent of males received special education services, and 7 percent of females did.

Hope

There is at least one subgroup of black Americans who are doing very well, according to a piece in The Root, a daily online magazine that provides thought-provoking commentary from a variety of black perspectives.

Here’s what it says:

“Despite it all, there is hope. There is a subgroup of black Americans who continue to achieve at high levels, results that might provide some clues to solving one of our most persistent educational problems. First- and second-generation immigrants from Africa and the Caribbean, though only 13 percent of the nation’s black population as a whole, represent 41 percent of all those of African descent at 28 selective universities and 23 percent of the black population at all public universities.

“Meanwhile, census data show that the children of these immigrants were more likely to be college-educated than any other immigrant or U.S.-born ethnic group, including white Americans.

“The success of these first- and second-generation black residents can be attributed to several factors, including where many of them choose to live as they raise families in the United States. In his seminal study, ‘Voluntary and Involuntary Minorities: A Cultural-Ecological Theory of School Performance With Some Implications for Education,’ John Ogbu, then a professor of anthropology at the University of California at Berkeley, contended that immigrant black Americans live in more racially diverse communities and aren’t burdened by perceived black underachievement on standardized tests.

“This is largely because they lack a connection to predominantly U.S.-born black communities and they trust white institutions more than non-immigrant black residents. This leads them to make housing choices based on the potential for greatest opportunity in education and employment, which tend to be in more diverse communities.”